Engine.



. Patented Dec. 30; I902. E. E. moms.

E N G l N E. (Apblication filed May 31, 1902.

4 Sheets-Sheet I.

(No Model.)

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Patented Dec, 30, i902. E. E. THOMAS.

E N GI N E.

Application filed. May 31, 1902.)

4 Sheets-Sheet 2.

(No Model.)

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Patenfed Dec. 30, m2.- E. E. THOMAS.

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(A pplication filed May 31, 1902.)

P atented Dec. 30, I902.

No. 7l7,l36.

E. E. THOMAS.

' ENGINE.

4 Sheets-Sheet 4 (Application filed May 31,, 1902.)

(N0 Model.)

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UNITED STATES PATENT OFFICE.

EDWVIN E. THOMAS, OF ST. PAUL, MINNESOTA, ASSIGNOR OF ONE-HALF TO UNIONIRON \VORKS, OF MINNEAPOLIS, MINNESOTA, A CORPORATION OF MINNESOTA.

ENGINE.

SPECIFICATION forming part of Letters Patent No. 717,136, dated December30, 1902.

Application filed May 31, 1902. Serial No. 109,629. (No model.)

1'0 all whom, it may concern:

Be it known that I, EDWIN E. THOMAS, of St. Paul, Ramsey county,Minnesota, have invented certain new and useful Improvements in Engines,of which the following is a specification.

My invention relates to engines that are capable of use wherever it isdesired to impart a reciprocating movement to mechanism, though designedparticularly for operating a gang-saw. This type of sawis usually drivenfrom a crank-shaft, and the speed of the gang is comparatively slow,making only about three hundred strokes per minute, a high speed withthe usual driving means or with an ordinary reciprocating-piston enginebeing practically impossible, owing to the danger of breakage arisingfrom too-rapid motion and the consequent vibration, momentum, and shockof the reciprocating parts.

The primary object, therefore, of my invention is to greatly increasethe capacity and efficiency of the gang-saw by providing means fordriving the same at more than double thespeed that can possibly beattained with any degree of safety by the ordinary driving mechanism nowemployed.

Other objects will appear from the following detailed description.

The invention consists generally in providing an engine of suchconstruction that a direct driving connection may with perfect safety bemade with the saw-gate.

Further, the invention consists in providing a steam-cylinder and anair-cylinder having pistons mounted on a common rod, and a piston-valvefor said steam-cylinder connected with the ends of the air-cylinder andadapted to be operated by the compression of the air therein toalternately admit'steam to the ends of the steam-cylinder.

Further, the invention consists in providing an air-cushion for thepiston-valve.

Further, the invention consists in an improved form of check-valve.

Further, the invention consists in various constructions andcombinations, all as hereinafter described, and particularly pointed outin the claims.

In the accompanying drawings, forming of Fig. 2. Fig. 4 is a section onthe line 00 a: of Fig. 1. Fig. 5 is a section on the line y 1 of Fig. 1.Fig. 6 is a detail of the check-valve.

Fig. 7 illustrates a modified and preferred form of valve andconnection.

In the drawings, 2 represents a suitable base, upon which I arrange anair-cylinder 3, having heads 4, provided with chambers or recesses 5 toreceive the reduced ends 6 of the cylinder-piston 7. These ends orauxiliary pistons moving in advance of the air-cylinder piston properallow the latter to approach close to the cylinder-heads and completeits stroke in each direction, and at the completion ofsuch stroke theair is compressed by said reduced ends sufficiently to operate thesteam-cylinder piston-valve. I prefer to employ these auxiliary pistonsin connection with the air-cylinder piston; otherwise if theair-passages led directly into the main portion of the cylinder the airmight be sufficiently compressed to operate the valve before theair-cylinder piston had completed its stroke.

- The cylinder is provided in its side walls with air-passages 8,leading from one end to the other and having plugs 9, by means of whichthe passages may be enlarged or contracted to regulate the volume of airpassing therethrough The openings leading to the passages are asufficient distance from the cylinder-heads to insure the requisitespace for an air-cushion between the piston 7 and the heads and preventcontact between them. This distance may be varied, according to thediameter of piston and its probable momentum. The air-cylinder piston isprovided with a rod 10, that extends up through a casting 11 and througha steam-cylinder12,mounted on said casting and preferably of lessdiameter than said air-cylinder and having a piston 13 also mounted onthe rod 10. Suitable stufiing-boxes 14, inclosing the pistonrod, areprovided in the heads of the steam- IOC cylinder. In the ends of thesteam-cylinder are ports and 16, communicating with a valve-casing 17,preferably provided on the side of the cylinder between the ports. Thisvalve-casing has annular passages 15 and 16, communicating,respectively, with the steamcylinder ports and with correspondingpassages 18 and 19, that lead, respectively, to the exhaust-pipes 20 andthe live-steam pipe 21. A sliding piston-valve 22 is provided withinsaid casing, having stems 23 projecting through the ends thereof topermit the operation of the valve byhand, if desired, and said valvecorresponds, substantially, to the valves of this type in general use inthat it has a series of annular grooves in its surface between whichbridges 24 and 25 are provided that form substantially steam -tightjoints with the wall of the casing and are adapted to alternately closethe passages between the steam-cylinder ports and the live-steam andexhaust pipes as the valve is reciprocated. Near the ends of thevalve-casing I provide air-ducts 26 and 27, which communicate with theinterior of the casing at a point near the ends thereof, but asufficient distance therefrom to afford space for an air-cushion toprevent the bridges 25 from coming in contact with the ends of thecasing.

The air-ducts are each provided with branch ducts 28, that lead intovalve-chambers 29, wherein I prefer to provide check-valves 30,

9 having wings 31, provided with notches 32 to -the duct 26.

allow the air to pass around them and normally resting upon a seat 33.At the upper end of these valves is a disk 34, that forms asubstantially close joint with the wall of the chamber and is providedwith small holes 35 between the wings. The upper end of the chamber ofeach valve is closed by a screwcap 36, and between said cap and the disk34 an air-cushion is formed to prevent the pound ing or hammering of thevalve in the chamber, the holes 35 allowing the air to slowly escape andpermitting the valve to rise from its seat and allow air to enter thechamber and pass through the branch duct 28 into The duct 26communicates with a pipe 37 below the valve-seat 33, and I prefer toprovide a plug 38 in each duct 26 to regulate the size of the openingtherein and the volume of the air passing therethrough. These plugs maybe adjusted to entirely close the lower end of the duct 26 and compelthe air to pass through the checkvalve, which closing thereafter willprevent premature escape of the air-cushion. The pipe 3'7 extends downbeside the air-cylinder and communicates With a port 39, provided in thewallof the chamber 5 thereof, and the duct at the opposite end of thevalve-casing 17 is provided with a pipe 37, which communicates with theport 39 in the chamber of the upper head of the air-cylinder. To controlthe volume of air passing through the pipes 37 and 37, I prefer toprovide plugs 40, acting as throttles to regulate the size of theopenings through the pipe, and hence the volume of air passingtherethrough to the valve. By means of these plugs or throttles I amable to regulate the volume of air delivered to the valve, according tothe size of the perfect working of the valve under ad-' verseconditions, such as grinding or sticking. I therefore provide anair-cylinder piston of sufficient area to insure the compression of avolume of air which will operate the valve under all circumstances, andto regulate the air so compressed and prevent an excess of pressure inthe valve-casing 1 prefer to provide a pipe 41, connecting the chambers5 in the air-chamber between the ports 39 and 39, so that the air aheadof the auxiliary piston as it enters its chamber may be conducted aroundthe piston to the opposite chamber, and the air so led around the pistonmay be regulated or shut off altogether by means of the plug 42 and thedesired airpressure on the valve easily obtained.

' In Fig. 7 I have shown a modification in the manner of conducting theair into the piston-valve casing and for cushioning the valve itself.This construction has advantages over that heretofore described, and Imay prefer to use it in practice. in dispensing with the check-valve andproviding air-ducts 26 in the ends of the valvecasing,through which theair is admitted from the pipes 37 and 37, and in one end of the casing Iprovide a dash-pot appliance, consisting of a cylinder 27, provided witha piston 27", that is secured on the valve-stem. An air-passage 28 isprovided in the wall of the cylinder 27, leading around the piston, anda plug 28" permits the regulation of the volume of air passing throughsaid passage. Where the air enters the valve-casing through its wall,there is a possibility of the valve when arrested by the air-cushionstopping over the port and preventing the intake of air to drive thevalve in the opposite direction. With the ports in the ends of thecasing this danger is entirely eliminated, and by providing the cylinderand piston on the end of the valve it is not necessary to regulate theadmission of air to the valve-casing to obtain the desired resistance ofthe cushion. The piston 27 will positively control the movement of thevalve, making its travel uni- 28 the resistance to the movement of saidpiston can be accurately gaged, according to the size of the valve andthe speed of the engine.

In Fig. l I have shown the apparatus connected to the gate of agang-saw, 43 representing the lower end of the gate, and 44 the Itconsists form and regular, and by means of the plug coupling connectingthe upper end of the piston-rod 1O thereto. This gate is verticallymovable in the frame 45 and carries a series of saws 46, that aresecured therein in the usual manner. 47 represents the feed-rollsoperated by the usual mechanism 48, that is common to machines of thischaracter, and hence requires no detailed description herein, the sameforming no part of my invention.

Upon each side of the saws are the pressure-rolls 4-9, carried in frames50, that are hinged on the framework 45 by means of lugs 5i and rods 52passing therethrough. The removal of one of these rods allows the frame50 on that side of the saw to be swung out to permit access to the saws.Upon the frame 50, on each side of the saws, are steam-cylinders 53,having sliding pistonvalves 54, controlled by a lever 55, that isconnected with said valve by a link 56 and a bell-crank 57. Thispressure-roll-operating mechanism and the manner of supporting the sameon the framework of the gang forms the subject-matter of a companionapplication herewith filed June 2, 1902, Serial No. 109,628, and I makeno claim to the invention in this application. Any suitable means may beprovided for supporting the gang above the operating-engine; but I haveshown horizontal timbers 58, supported upon posts 59, that rest upon abase (50.

The operation of my improved engine or gang operating mechanism is asfollows: Steam being admitted through the port 16 beneath thesteam-cylinder piston, both pistons will be raised to the upper ends oftheir cylinders. As the piston 7 opens the passages S behind itin itsupward movement the air in front will be allowed to pass around to therear of the piston, and no compression will take place until the piston7 has closed the upper inlet-openings to the air-passages. From thispoint on toward the cylinder-head the air will be compressed and willact as a cushion to take up the momentum of the rapidly-moving parts andprevent shock and damage to the machinery arising from the contact ofthe pistons with the cylinderheads. As the piston 7 approaches the pointwhere it will close the air-passages leading around to it the reducedend 6 will enter the chamber or recess in the cylinder-head andcompressing the air therein will force it up through the pipe 3'7 andthe air-duct 27 into the valve-casing and move the valve toward theopposite end until its motion is arrested by the air-cushion or by thepiston and cylinder device heretofore referred to. The travel of thevalve, however, before being stopped will be sufficient to close thepassage leading from the live-steam pipe to the port 16 and open thepassage from said pipe to the port 15. Steam will then enter thesteamcylinder above its piston, and both pistons will immediately beginto descend. The piston 7, approaching the lower head 4, will,

as before described with reference to its opposite movement, allow theair to escape until the piston passes the open mouths of theair-passages and approaches the cylinder-head, when the cushion will beformed as before and the momentum and shock taken up. The air will bedriven through the pipe 37 into the right-hand end of the valve chamberor casing behind the valve, which will be moved toward the left, closingthe upper steam-port to the live steam and opening it to the exhaust. Itmay be necessary in starting to set the valve by hand; but after thatthe valve and engine will continue to operate until steam is shut offfrom the steam-cylinder. The valve will automatically adjustitself toits different positions, and should it for any reason during theoperation of the engine get out of stroke and not move in unison withthe reciprocating pistons it can be readily set by hand.

I have shown my improved form of engine adapted for use with a gang-saw;but it will be understood that it is equally applicable wherever it isdesired to drive a reciprocating mechanism at a higher speed than wouldbe practicable for the appliances that have heretofore been used forthis purpose.

I claim as my invention 1. An engine, comprisinga steam and an aircylinder provided with pistons on a common rod, the air-cylinder pistonhaving re duced extensions forming auxiliary pistons on each end, saidaircylinder having chambers in its ends corresponding in form andadapted to receive said reduced extensions, a floating piston-valve opento the steam supply and exhaust and having passages communicatingrespectively with the ends of said steam-cylinder and with the chambersin the ends of said air-cylinder.

2. An engine, comprising a steam and an air cylinder provided withpistons on a common rod, said air-cylinder being provided in its wallwith air-passages leading past the middle thereof and opening into theends near the cylinder-heads and having means for regulating the volumeof air passing therethrough, a sliding piston-valve having ports in itscasing communicating with the steam supply and the exhaust, ducts orpassages leading from said valve and communicating respectively with theends of said cylinders and a cushion stop device connected with saidvalve.

An engine, comprising a steam and an air cylinder provided with pistonson a common rod, the air-cylinder piston having reduced extensions oneach end and said aircylinder having air-passages in its walls leadingaround its piston from one end to the other, and means for regulatingthe flow of air therethrough, the ends of said air-cylinder havingchambers corresponding in form and adapted to receive said reducedextensions, and the openings leading to said airpassages being asufficient distance from the T &

heads of the main portion of said air-cylinder to allow for theformation of air-cushions between said heads and the middle portion ofsaid piston, a sliding valve having its casing provided with portscommunicating with the exhaust and the live steam, and suitable passagesor ducts leading from said valve to said steam-cylinder and to saidchambers.

4. An engine, comprising a steam and an air cylinder having theirpistons on a common rod, a floating piston-valve open to the steam andexhaust pipes and having passages communicatin g respectively with theends of said cylinders and adapted when reciprocated to alternately shutoff the admission of steam to the steam-cylinder passages and open themto the exhaust, and a cushion stop device connected with said valve.

5. An engine, comprising a steam and an air cylinder provided withpistons on a common rod, said air-cylinder having chambers in its endsto receive correspondinglyshaped extensions on the opposite sides of itspiston, a sliding piston-valve open to the steam supply and exhaust andcommunicating respectively with said steam-cylinder and with saidchambers.

6. An engine, comprising a steam and an air cylinder having theirpistons connected, a sliding piston-valve having passages communicatingrespectively with the ends of said cylinders and adapted whenreciprocated by the compression of the air in the ends of saidair-cylinder to alternately shut off the admission of steam to thesteam-cylinder passages and open them to the exhaust, and an air cushionstop device connected with said valve.

7. An engine, comprising a steam and an air cylinder having'theirpistons on a common rod, a sliding piston-valve open to the steam andexhaust pipes and having passages communicating respectively with theends of said cylinders and adapted when reciprocated by the pressure ofthe air generated by the movement of said air-cylinder piston toalternately shut off the admission of steam to the steamcylinderpassages and open them to the exhaust, and a cylinder provided at oneend of said valve and having its piston connected with said valve-stem.

8. An engine, comprising a steam and an air cylinder having theirpistons connected, a sliding piston-valve having passages communicatingrespectively with the ends of said cylinders, a cushion stop devicecomprising a cylinder provided at the end of said valve and having itspiston connected with the stem thereof, and an air-duct in the Wall ofsaid cushion stop-cylinder leading around its piston and having asuitable throttle whereby the resistance of the cushion to the movementof the valve may be controlled.

In witness whereof I have hereunto set my hand this 27th day of May,1902.

EDWIN E. THOMAS.

-In presence of- RICHARD PAUL, M. O. NooNAN.

